This invention relates to liquid storage containers for manually dispensing liquids such as cleaning solutions for contact lenses, and more particularly relates to dispensing nozzles on containers for liquid which must be stored in generally sterile conditions.
Liquids, for example, solutions for cleaning and conditioning contact lenses, have typically been stored in manually squeezable bottles from which the user can repeatedly dispense the stored liquid. The liquid must be uncontaminated by microorganisms such as bacteria. Accordingly, expensive bacteriacidal agents have often been included in the liquid formulation, for example, saline formulations for cleaning contact lenses. Furthermore, the squeezable dispensing bottles have sometimes been provided with nozzles including filter membranes which are permeable to the dispensed liquid as well as being permeable to the air which must be aspirated through the nozzle to replace the dispensed liquid and reinflate or re-expand the container. The filter membrane must be impermeable to bacteria in order to prevent the aspirated air from carrying bacteria into contact with the stored solution, so that the solution is maintained in sterile condition for repeated dispensing. However, filter membrane materials which are sufficiently hydrophilic to permit permeation of the saline solution often permit retention of the saline solution on the filter so that the retained solution increases the resistance of the filter to passage of the aspirating air. The partially obstructed flow of aspirating air not only retards the re-expansion of the squeezed bottle wall, but also impedes repeated squeezing of the bottle when large quantities of the solution must be dispensed. When portions of the filter are treated to repel the solution and improve air passage, the solution can sometimes leach the treating composition from the filter.
According to the subject invention, a nozzle assembly provides improved air aspiration of the squeezed liquid dispensing container for improved convenience to the user, particularly in repeated dispensing of the solutions for contact lenses.